<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      input {
        outline: none;
      }
    </style>
  </head>
  <body>
    <div class="search">
      <input type="text" />
      <button>搜索</button>
    </div>
    <script>
      var input = document.querySelector("input");
      document.addEventListener("keyup", function (e) {
        if (e.keyCode == 83) {
          input.focus();
        }
      });
    </script>
  </body>
</html>
